update DBSUser to accept DN, such as /DC=com/DC=DigiCert-Grid/O=Open Science Grid/OU=People/CN=Bockjoo Kim 118811 and O'Reilly
Merge pull request #5234 from yuyiguo/lexicon-DBSuser

update DBSUser to accept DN, such as /DC=com/DC=DigiCert-Grid/O=Open Sci...